U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Search Publications by: George D. Quinn (Assoc)

Search Title, Abstract, Conference, Citation, Keyword or Author
Displaying 26 - 50 of 62

Machining Cracks in Finished Ceramics

May 16, 2005
Author(s)
George D. Quinn, L K. Ives, S Jahanmir
Well prepared strength test specimens and components break from a material s inherent flaws and machining damage has no effect on strength. On the other hand, grinding can create machining flaws that control strength and limit the performance of finished

Fracture Mirrors in a Nanoscale 3Y-TZP

March 1, 2004
Author(s)
George D. Quinn, J Eichler, U Eisele, J Rodel
The strengths of fine microstructural scale yttria stabilized rectangular bars and circular disks were measured by four-point flexure and by flat ball (piston) on three ball methods. Fracture mirror sizes were measured and correlated to the strengths

Machining Cracks Revealed by Fractography

August 28, 2003
Author(s)
George D. Quinn, L K. Ives, S Jahanmir
Fractography detected and characterized the nature and size of strength limiting rods and bars in a sintered reaction bonder silicon nitride that was ground by a variety of procedures.

Fracture Toughness of Toughened Silicon Nitride by ASTM C 1421

June 1, 2003
Author(s)
George D. Quinn, J Swab, M J. Motyka
The fracture toughness of a commercial sintered reaction-bonded silicon nitride was measured by the three complementary test methods in ASTM C 1421. Precracks ranged from tiny artificial flaws introduced by Knoop indentation to millimeter long precracks in

Cracking and the Indentation Size Effect for Knoop Hardness of Glasses

March 1, 2003
Author(s)
George D. Quinn, P Green, K Xu
The Knoop Hardness of five glasses as measured over a wide range of indentation loads. Hardness decreased with increasing load in accordance with the classic indentation size effect (ISE). At moderate loads, cracking dramatically altered the indentation

Machining Damage Cracks: How to Find and Characterize Them by Fractography

January 1, 2003
Author(s)
George D. Quinn, L K. Ives, S Jahanmir
Subsurface machining cracks may control strength and performance of finished ceramics. Previously, machining cracks had been though to be difficult or impossible to detect and characterize, especially in toughened ceramics with interlocking grain

Mechanical Testing for Ceramics

January 1, 2003
Author(s)
George D. Quinn
This article describes (briefly) the common tests used for strength testing of ceramics.

Weibull Strength Scaling for Standardized Rectangular Flexure Specimens

January 1, 2003
Author(s)
George D. Quinn
Formulas for the effective volumes and effective surfaces for rectangular bars loaded in flexure are reviewed. The ratio of strengths from any two configurations, such as 3-point flexural to 4-point, is independent of whether the flaws are volume or

Effect of Loading Rate Upon Conventional Ceramic Microindentation Hardness

June 1, 2002
Author(s)
George D. Quinn, P J. Patel, Isabel K. Lloyd
Dynamic micro-indentation hardness was evaluated for a steel, sintered silicon carbide, and an aluminum oxynitride. There was negligible effect upon Vickers hardness when loading rate was varied by almost three orders of magnitude.

The Fracture Toughness Round Robins in VAMAS: What We Have Learned

January 1, 2002
Author(s)
George D. Quinn
Over the last thirteen years the Versailles Advanced Materials and Standards (VAMAS) project has conducted five full fledged, international round robins on ceramic fracture toughness characterization. As many as forty laboratories have done thousands of

Comparisons of Calculated and Measured Flaw Sizes

October 1, 2001
Author(s)
George D. Quinn, J Swab
Fracture mechanics often is applied in fractographic analyses in order to verigy that the correct feature has been identified as the fracture origin. This step has been codified in ASTM Standard C1322-96, Standard Practice for the Characterization of

Fractographic Analysis of Machining Cracks in Silicon Nitride Rods and Bars

October 1, 2001
Author(s)
George D. Quinn, L K. Ives, S Jahanmir, P Koshy
A new fixture for flexural strength testing was used to evaluate the effects of machining on the flexural strength of a toughened sintered reaction-bonded silicon nitride. Different grinding procedures had various effects upon the flexure strength

Using X-Ray Topography to Study Fracture of Single-Crystal Ceramics

October 1, 2001
Author(s)
David R. Black, Robert S. Polvani, George D. Quinn
X-ray topography provides a unique view of the surfaces of single-crystal samples, both before and after fracture. The diffraction topograph, which is sensitive to local strain and/or crystallographic orientation, can be used to inspect samples prior to

Standard Reference Material 2100: Fracture Toughness of Ceramics

June 1, 2001
Author(s)
George D. Quinn, K Xu, R J. Gettings, J A. Salem, J Swab
New Standard Reference Material (SRM) 2100 is the first reference material in the world for the property fracture toughness for any class material. The SRM is for ceramic fracture toughness and may be used with any ceramic fracture toughness test method